Method for manufacturing barber scissors, and barber scissors

ABSTRACT

The invention relates to a method for manufacturing barber scissors, wherein the scissor blades are pre-shaped from blanks by a predetermined degree of curvature in the direction facing away from the edge. This is followed by a step of welding on a hard metal material in the form of a welding bead on respective mutually facing faces of the scissor blades in order to form the edges, wherein the preliminary curvature of the scissor blades is neutralized owing to the influence of heat during the welding process. Subsequently the welding beads are ground so as to form the edges, and the scissor halves are pre-set and hardened. Then the barber scissors are hard-set in the assembled condition. The invention furthermore relates to barber scissors having such a configuration. Here the edges are present as massive material over the entire thickness of the scissor blades, so that even severally repeated re-grinding or re-setting of the barber scissors is possible without any loss of functionality.

This is a Continuation of application Ser. No. 10/531,688 filed Apr. 15,2005, which in turn is a National Stage of PCT, which claims the benefitof PCT Application No. PCT/EP03/011447 filed Oct. 15, 2003. Thedisclosures of the prior applications are hereby incorporated byreference herein in their entirety.

The invention concerns a barber scissors.

Scissors conventionally are comprised of two scissor halvesarticulatedly interconnected through the intermediary of a lock, withthe two scissor halves, and thus also the edges, frequently being formedof stainless or stain-resistant steel alloys. Such scissors do, however,present the drawback of losing their sharpness in the range of the edgesafter a relatively short period of use. For this reason it is also knownto apply hard metal layers in the range of the edges. Hereby thelifetime of the scissors may be extended substantially, with the edgepreserving its sharpness longer thanks to the strength of the hardmetal. On the other hand, however, hard metal is relatively brittle,which is the reason why the production step for setting the barberscissors is more difficult to perform than with conventional scissorblades of steel alloys. Excessively intense processing and the resultingdeformation may result in cracks and chipping at the edge. On the otherhand, uniformity of movement and smoothness of the two scissor partsdepend on optimum mutual setting of the scissor blades. If hard metal isat all employed for the edges, it is therefore preferred in practice toconcentrate this material in the range of the edges.

In addition, various types of scissors are known in practice, each ofwhich are based on the same fundamental principle, however are subjectto clearly distinct requirements depending on their application. Thus itis substantially of importance in the case of a conventional pair ofhousehold scissors that they may be provided at low cost and severpaper, cloth, etc. with satisfactory results. Apart from this there are,for example, also surgical scissors whereby specific cuts are possibleeven in hard-to-cut body tissue in the course of a surgicalintervention. To this end, these scissors customarily comprise longshanks with short edges so as to obtain favorable conditions ofleverage, and are moreover formed of materials that are particularlycorrosion resistant and also endure sterilization processes. Frompractical use, surgical scissors are moreover known where hard metaledges are joined to the scissor blades, or hard metal plateletsconstituting hard metal edges are attached at the scissor blade in orderto ensure the cutting properties even with hard or resistant organicmaterials, in particular also over the entire duration of one or severalsurgical operations. The use of hard metal edges has found goodacceptance in this field, particularly due to the fact that surgicalscissors are subject to very high fretting corrosion in the range of theedges, for the scissors must not be oiled following sterilization forreasons of hygiene. As it is, however, only sparsely necessary to placecuts in surgery, the unfavorable frictional conditions at the edges ofthe like surgical scissors are only of minor importance in practice,also with a view to the favorable leverage conditions.

In the case of barber scissors, in contrast, easy movement of thescissors is of eminent importance, for they represent the essentialworking tool for a hairdresser. They are massively utilized in thecourse of one workday, and hundreds or even thousands of single cutsmust be carried out with them day in, day out. In order to allow foragreeable working with such barber scissors, even in the light of thehigh cutting frequencies, their scissor blades should be set withparticular precision and designed for low friction, so that the effortimplied for each single cutting process may be kept low.

To this end it is in particular known in practice to cross the scissorblades in such a way that the two edges will with maximum accuracyalways contact each other in precisely one point when a cut isperformed, with this point of contact progressively migrating to thefront tip of the scissors while the scissor halves are being closed.Such crossing of the scissor blades is achieved by a torsion thereofabout their longitudinal axes on the one hand, and by bending themtowards each other on the other hand. This setting of conventionalbarber scissors is carried out in the hardened and locked condition,with the smooth movement of the two edges being influenced and optimizedthrough gentle hammer strokes. There are, however, limits to this mannerof proceeding, as well, for the edge tends to become damaged if workedtoo strongly with the resulting deformation. There are accordinglylimits to an optimization of homogeneity of movement and to the easymovement of the two scissor parts in conventional barber scissors.

In addition, barber scissors thus formed may only be manufactured withhigh complexity, for which reason they are very expensive. They aremoreover also very sensitive, for even a single drop on the floor mayresult in a deformation of the scissor blades, which will bring about amassive impairment of the moving properties of the two edges even in thecase of a slight deformation. Manipulation of the barber scissors willthen become considerably more difficult, so that as a general rule theywill be made useless even after one such impact due to an impairedprecision and movement and accuracy.

One example for barber scissors with hard metal edges may be found in DE199 09 887 A1. The hard metal is here applied as a layer on a basematerial by a thermal spraying method and subsequently ground so as toobtain the slide face and the shear edge. As a result of the applicationof such a wear-reducing layer of hard metal, the edges are not sosensitive to wear and will not blunt as quickly as conventional barberscissors. In the long run they therefore exhibit reduced resistance uponclosing of the scissors, so that the effort required from the user willequally be permanently low. Such barber scissors equipped with hardmetal edges even allow to cut other materials such as paper or the like,without losing the cutting performance on hair.

A deformation owing to mechanical influences such as, e.g., a drop ofthe barber scissors on the floor does, however, in the case of thebarber scissors with hard metal edges as known from DE 199 09 887 A1have the result that it will as a general rule not be usable any more,for the connection of the sprayed-on hard metal layer with the base bodydoes not have sufficient stability to allow for post-processing. Wherethe hard metal layer is not already broken away due to the impact, themechanical action during renewed setting of the edges of these barberscissors mostly causes the hard metal layer to chip off.

The insufficient adhesion of the sprayed-on hard metal layer on the basebody is also the reason why even the first setting of these conventionalbarber scissors is problematic. It is necessary to proceed with utmostcare in order to limit the percentage of refuse. For this reason, areduced quality of the final product is commonly accepted in order tokeep the production costs as a whole within an acceptable frame.

It is another drawback of the hard metal-coated barber scissors inaccordance with DE 199 09 887 A1 that resharpening of the edges bygrinding as a general rule is at best only possible once, for theapplied material is removed in the process, with the edge subsequentlyagain only be constituted of the less suitable carrier material.

The invention is therefore based on the object of furnishing a methodpermitting the manufacture of easy-moving barber scissors having a longlifetime and high mechanical strength, with the possibility of repeatedsubsequent sharpening of the shear edge. Moreover it is intended tofurnish such barber scissors.

This object is attained through barber scissors having the featuresdiscussed below.

A method of the invention for manufacturing barber scissors provides thefollowing steps: furnishing one blank each for scissor halves of thebarber scissors, with the scissor halves each comprising a scissorblade, a shank, and a ring, pre-shaping the scissor blades by apredetermined degree of curvature in the direction facing away from theedge, welding on a hard metal material in the form of a welding bead onthe respective mutually facing faces of the scissor blades in order toform the hard metal layers for the edges, wherein the predeterminedpre-forming of the scissor blades is substantially neutralized owing tothe influence of heat during the welding process, grinding of thewelding beads so as to form the edges, combining and subsequentlysetting the scissor halves, disassembly and subsequent hardening of thescissor halves, surface treatment of the scissor halves, again combiningthe scissor halves, and hard-setting the barber scissors.

Here it was realized in accordance with the invention that despite thehigh quality demands to the scissor blades of barber scissors, it ispossible to apply the material for the edges by welding on a hard metalmaterial, or hard-facing, if the deformation of the blank due to thethermal influence during the welding process is specifically taken intoconsideration. In accordance with the invention this is achieved by thepre-shaping of the scissor blades, wherein it is possible to reliablyperform such pre-setting, for the weld is applied on the full surface onthe front side of the scissor blade, resulting in a heat flux and thusin a curvature in only one direction. The curving behavior of the blankunder the thermal influence during the welding process may thus bepredetermined well. This pre-forming is substantially neutralized in thefollowing welding step, so that substantial stresses will not remainwithin the material of the scissor blades, and the edges neverthelesswill have a suitable relative arrangement in the cooled condition of thescissor halves while allowing their formation by grinding of the scissorblades. The scissor blades thus formed accordingly have edges whichextend over the entire thickness of the scissor blades and are formed asmassive elements. It is therefore possible to carry out even severallyrepeated sharpening of the edge by grinding.

The barber scissors in accordance with the invention accordingly keeptheir sharpness over a long period or may be resharpened while movingvery easily, for such hard metals produce little friction running oneach other. In particularly it is also possible with the barber scissorsof the invention to grind the edges to a very acute angle, resulting ina razor-sharp edge where this is desired. In the case of edges of softermaterials the tip of the cutting angle is subject to very high wear,resulting in a rapidly reduced sharpness, whereas in accordance with theinvention, by using a hard metal edge of the barber scissors formed ofmassive material, it is possible to reliably prevent the chipping off ofa tiny piece when the edges run against each other. In conventionalbarber scissors this habitually results in their becoming useless, forthe faulty location will damage the opposite edge due to the createdrecess or irregularity. This set of problems may be avoided with thebarber scissors of the invention that include hard metal edges.

Furthermore the barber scissors of the invention are characterized inthat the edge is subject to low wear, resulting in prolonged durabilityat an identical cutting performance. Moreover the continuous hard metallayer is also prone to corrosion in a lesser degree, which equallyimproves its durability. It is therefore also possible to cut foreignmaterials without a loss of cutting properties. These may even be thinwires, paper, or similar materials, for unevennesses or damages at theedge may be avoided thanks to the continuous hard metal material, or beremedied by regrinding and optionally by resetting.

It is moreover particularly advantageous in the technique in accordancewith the invention that thanks to the welding process, a particularlygood and reliable connection is produced, for in the range of the weldthere results a kind of alloy of the base material fused with the hardmetal material. Hereby mechanical as well as thermal stresses in thematerial may be avoided, or a more homogeneous transition between thecombined materials may be produced. Chipping of an edge from the scissorblade may thus reliably be precluded, so that particularly accuratesetting and fine trimming of the edges is possible even by hammerstrokes. Should this become necessary, for instance after the scissorsfell to the ground, barber scissors may therefore readily be resetaltogether.

It is another advantage of the method in accordance with the inventionthat the welding bead, or the edge ground on at least two sides, may beexamined with a view to possible pores in the hard metal or otherwelding defects. Such deficiencies may therefore be recognized better,so that it is possible to guarantee a substantially higher productquality.

Moreover the degree of pre-curving for the pre-forming of the scissorblades may be determined with relatively low complexity, in whichcontext it is possible, for instance, to carry out test welds on blanksfor each batch. This is based on the consideration that the degree ofdeformation may vary slightly between batches, and it is possible toobtain corresponding values of experience with low technicalexpenditure. Once pre-forming has been determined in a series of ascissors type of the invention, this value may be transferred to theremaining scissor parts of this batch of blanks.

The method of the invention may thus be performed with high reliabilityand relatively low technical expenditure. In particular it is therebypossible to manufacture barber scissors having particularly advantageousproperties.

Advantageous developments of the method of the invention are discussedfurther below.

Thus the blank of a scissors half may already be formed such that thehard metal material may be applied directly onto the mutually facingfaces of the scissor blades. As an alternative it is, however, alsopossible to perform a removal of material on the scissor blades prior totheir pre-forming on the mutually facing faces, on which the edges areto be formed. This removal of material may readily be accomplished bygrinding or milling and produces an improved base for the welding beadof hard metal material to be applied thereon. The method of theinvention may thereby be performed with even higher reliability andquality safety.

For welding on the hard metal material in particular a TIG (tungsteninert gas) welding process has found acceptance in practical testing,for hereby a good connection and a high-quality welding bead may beproduced. Besides this, however, another inert gas welding process mayequally be applied.

If welding on of the hard metal material is performed with the aid of acooled clamping device, the process may be controlled even moreaccurately, whereby it is possible to avoid an impairment by the thermalinfluence particularly of the carrier material of which the scissorblades are formed, and the heat fluxes may be controlled better.

Furthermore it is also possible that hard-setting of the barber scissorsencompasses a pre-setting by means of hammer blows. This method, whichis already known per se and found acceptance in practice forconventional barber scissors, has moreover—contrary to the badexperiences with-on hard metal layers—shown itself to be advantageousfor welded-on hard metal edges of massive material, as was found inpractical tests performed by the present applicant. In this way a goodand regular movement of the two edges is made possible with relativelylow complexity in production technology.

Due to the fact that the surface treatment of the scissor halvesincludes a fine grinding in one step or in several steps, with theinsides of the scissor blades and of the edges being worked on a corkdisc while using a polishing powder and a polishing paste, easy movementof the barber scissors manufactured by this method may again be improvedsubstantially. The two scissor blades slide even more easily on eachother, whereby the effort for cutting may be further reduced. Here it ispossible to progressively approach the optimum of easy movement of thescissors by the minute removal of material, which is not possible in theconventional machining method, particularly in the case of hardmetal-coated scissors.

It is furthermore advantageous if the surface treatment of the scissorhalves includes matting of the insides of the scissor blades and of theedges by means of a Scotch disc. Minor grinding traces possibly stillexisting after the fine grinding step, which may even be felt in themovement of the scissors, may thus be removed and reduced to such adegree that they cease to influence a smooth movement of the scissors.Furthermore it is hereby also possible to obtain an enhanced corrosionstrength of the surface.

In accordance with another aspect of the present invention, barberscissors are furnished. They are in particular manufactured by a methodas discussed above, and further below. It is characterized in that theedges are provided as elements of massive material on mutually facingfaces of the scissor blades which are formed by weld application of ahard metal and subsequent grinding step, and extend over the entirethickness of the scissor blades.

The barber scissors of the invention are thus characterized by excellentcutting properties at high resistance against mechanical strains, longlife, and particularly also by the ability of permanently remainingsharp even at an acute cutting angle, and where necessary also by theability of readily being resharpened. Further advantages of the barberscissors of the invention result from the aspects discussed in thepreceding with regard to the method.

This particularly also applies to developments according to which theinsides of the scissor blades and of the edges are fine-ground and/ormatted, to thus improve easy movement of the barber scissors and/ortheir corrosion resistance.

Furthermore in practical experiments a hard metal material for the edgeswas found to be particularly advantageous which consists of acobalt-based alloy. Particularly good results were obtained in testswith an alloy including 30% of Cr, 12% of W, 2.5% of C, and theremainder Co (Stellite 1), which has a hardness HRC of 51 to 58. Withthis material the advantageous properties of the barber scissors of theinvention may be optimized particularly well.

The invention shall in the following be explained in more detail by wayof practical examples by referring to the figures of the drawing,wherein:

FIG. 1 shows barber scissors of the invention in the closed condition;

FIG. 2 shows the barber scissors of the invention in the openedcondition;

FIGS. 3A to 3C show manufacturing steps by the example of one scissorhalf.

In accordance with the representations in FIGS. 1 and 2, barber scissors1 comprise two scissor halves 2 and 3 pivotally coupled to each otherthrough the intermediary of a lock 4. The scissor half 2 includes a ring21, a shank 22, a scissor blade 23, and an edge 24. In addition a bladestop 25 as well as a finger support 26 are furthermore arranged on thering 21. The scissor half 3 includes a ring 31, a shank 32, a scissorblade 33, and an edge 34.

The manufacturing method for the barber scissors 1 shall in thefollowing be explained by referring to FIGS. 3A to 3C by the example ofscissor half 2, with the method for scissor half 3 unfoldinganalogously.

Initially the two scissor halves 2 and 3 are furnished and processed ina traditional manner known per se. Thus in particular even at thebeginning of processing, a grinding and polishing of the inner face ofthe rings 21 and 31, and a formation of the bores in the two scissorhalves 2 and 3 while cutting a thread and countersinking the screw holeon the matching part for the lock 4 having the form of a bolt areperformed. This is followed by the actual steps of forming the edges 24and 34.

In accordance with the representation in FIG. 3A, at first a blank forthe scissor half 2 is furnished. The scissor blade 23 is left in therange intended for formation of the edge 24. Then the scissor blade 23is shaped such that it is curved away from the edge approximately intothe position indicated by a dashed line in FIG. 3A. The degree of thispreliminary curvature was determined in preliminary testing andcorresponds to a degree of deformation of the scissor blade owing to theinfluence of heat during the subsequent welding process.

In accordance with the representation in FIG. 3B, a hard metal materialis then applied in the form of a welding bead 5 on the associated faceof the scissor blade 23 by a TIG welding process. From this welding bead5 the edge 24 will later on be formed by a grinding step. The adjacentsurfaces of the scissor blade 23 and of the edge 24 are ground jointly,resulting in an aligned transition. This is of particular importance onthe inside of scissor blade 23 facing scissor blade 24, for thesesurfaces can slide on each other. The width of the edge 24 in the topview of the barber scissors 1 is on the average about half the width ofscissor blade 23.

In the scissor half 2 thus produced, the scissor blade 23 and the edge24 are thus intimately connected, with the softer material of thescissor blade 23 permitting accurate setting of the barber scissors 1 inthe assembled condition, and wherein the good wear resistance of thehard metal material of the edge 24 provides for a long service life withpermanently good cutting properties.

For the purpose of setting, the two scissor halves 2 and 3 are screwedtogether and connected and then set jointly. The setting stepparticularly concerns movement and shape of the edges 24 and 34 and ofthe scissor blades 23 and 33, as well as the rings 21 and 31 and thebranches. Here the rings are also bent into the desired shape and adesired angle of inclination with the main plane of the scissors so thatthese lie well in the hand. Finally the scissor halves 2 and 3 areprovided with numbering in order to ensure their association, followingby global pre-grinding of the shape on the barber scissors 1. Hereuponthe scissor halves 2 and 3 are again taken apart and washed in anultrasonic bath at approx. 80° C., and subsequently rinsed with water.

After this, the scissor halves 2 and 3 are hardened. This is followed bypolishing the insides of the scissor blades 23 and 33 on a cork discwith polishing paste, as well as the lock on the two scissor halves 2and 3. These are then in turn connected with each other and subsequentlyhard-setting is performed. Here the running surface is polished, and theshape is optimized particularly with a view to the relative position ofthe two scissor blades 23 and 33, and to the position of the rings 21and 31. Subsequently the scissors are pre-ground entirely and afterwardspolished, for which purpose a grain size 400 or 600 is used.

In a subsequent step, the two scissor halves 2 and 3 are then againtaken apart and once more surface-treated by brushing with the aid of abrush disc and brushing powder. This is followed by a cleaning step ofthe parts. Then the scissor halves 2 and 3 are finished with the aid ofa wobble disc and finishing paste, and the insides of the scissor blades23 and 33 are matted. As a result of these finishing steps, the surfacesare homogenized and given an optically appealing appearance.

This is followed by a renewed cleaning step of the scissor halves 2 and3 and renewed combination of the latter in accordance with theassociated numbers on the parts. Subsequently setting of the barberscissors 1 is completed, the bolt serving as the lock 4 is appropriatelytightened such that the shank of the bolt bites into the thread to bepermanently fixed, and the running surface is set. Afterwards, wherenecessary, renewed grinding and polishing of the hard metal edges 24 and34 as well as cleaning of the parts are performed.

In the present embodiment, this is followed by a step of gold-platingparts of the barber scissors 1, with the gold locations being coveredwith adhesive tape or the like, the bolt is polished and ground with afelt wheel, and the bolt and scissor halves 2 and 3 are subjected to thegold-plating after another cleaning step.

After this the blade stop 25 and the finger support 26 are applied, anda renewed movement check as well as optionally re-grinding of the edges24 and 34 are performed. This is followed by a cutting check and aquality test of the entire product, which is subsequently oiled so as toprevent corrosion; the scissors are then wiped, packaged, and readiedfor shipping.

Apart from the explained embodiment, the invention allows for furtherconfiguration approaches.

Thus the barber scissors 1 of the invention may in the screwed-togethercondition at first be pre-set in a conventional manner with a hammer soas to establish a certain degree of advantageous accuracy of movementand precision.

Furthermore the step of grinding the scissor blades 23 and 33 and theedges 24 and 34 may be followed by fine-grinding in one step or inseveral steps. In this fine-grinding step, the mutually facing insidesof the scissor blades 23 and 33 and of the edges 24 and 34 arepost-processed on a cork disc having a thickness, e.g., of 20 mm, at1200 rpm while using a special, very fine polishing powder.

Apart from this, the insides of the scissor blades and of the edges mayin a further method step be matted with the aid of a Scotch disc so asto remove any minor grinding traces possibly still existing even afterthe fine grinding and polishing steps while removing them to such adegree that they will not impair a smooth movement of the scissors anymore.

It is also advantageously possible with the method in accordance withthe invention to include the range of the scissor halves 2 and 3 aroundthe lock 4, in which these slide on each other and guide each other, inthe grinding and/or matting steps provided in the method of theinvention.

Besides the TIG welding process as explained, it is also possible toemploy other welding processes for applying the welding bead of hardmetal material, wherein an inert gas welding process such as TP, MIG, orMAG welding is preferred. Moreover it is also possible to performhard-plating with the hard metal material by using a cooled clampingdevice.

A material that was found to be suitable in testing for the hard metalis in particular a cobalt-based alloy. Advantageously, stellites areused for this purpose, with hard metal having a hardness HRC in therange of 50 to 60 being particularly suitable. Thus it is possible,besides Stellite 1, to also use Stellite 4 H or Stellite 190 etc., forinstance. Apart from this it is, however, also possible to use any otherhard metals having equivalent properties.

1. Barber scissors comprising two scissor halves each including ascissor blade, a shank, and a ring and articulatedly coupled with eachother in an articulation by means of a lock, and including edges of hardmetal on each scissor blade, wherein the edges: are formed by weldingapplication of a hard metal and a subsequent grinding step, are formedas massive elements, extend over an entire thickness of the scissorblades, and are provided on mutually facing front faces of the scissorblades.
 2. The barber scissors in accordance with claim 1, wherein theinsides of the scissor blades and of the edges have a fine-groundsurface.
 3. The barber scissors in accordance with claim 1, wherein theinsides of the scissor blades and of the edges have a matted surface. 4.The barber scissors in accordance with claim 1, wherein the hard metalof the edges is comprised of a cobalt-based alloy.
 5. The barberscissors in accordance with claim 4, wherein the cobalt-based alloycomprises 30% of Cr, 12% of W, 2.5% of C and the remainder Co, thecobalt-based alloy having an HRC hardness between 51 and 58.